1. Field of the Invention
The present invention relates to a method of assessing surface quality, and more particularly to a method of assessing the quality of a surface of a fuel injector assembly proximate a valve sealing area.
2. Background Art
Fuel injection systems are used to provide fuel to an engine of a motor vehicle. A fuel injection system includes one or more fuel injector assemblies. A fuel injector assembly includes one or more valves for controlling the injection of fuel. The valve is configured to permit the injection of fuel when closed and seal against a mating surface of the fuel injector assembly to inhibit fuel injection when open. Defects along or near the mating surface such as pitting, chipping, or erosion, may result in undesirable fuel leakage and degrade the performance of the fuel injector assembly.
Previously, visual inspection was used to assess surface attributes of a fuel injector assembly. More specifically, the mating surface of the fuel injector assembly was magnified under 50× magnification and visually inspected for surface defects. Such visual inspections were problematic since they involved subjective assessments of surface quality. In particular, subjective assessments resulted in the improper rejection of acceptable fuel injector assemblies and acceptance of defective fuel injector assemblies. Such improper rejections reduced process yields and increased manufacturing and warranty costs.
Before applicant's invention, an improved method of assessing the quality of a surface of fuel injector assembly was needed. Moreover, a method of assessing surface quality near a sealing surface without subjective visual assessments was needed. In addition, a method that could accurately assess the quality of one or more fuel injector surfaces having tight surface finish tolerances was needed. In addition, a method that could quickly and accurately assess surface quality in a small area without deforming or damaging the surface was needed. In addition, a method that was compatible with a high-volume fuel injector manufacturing system was needed to improve manufacturing process efficiency. Problems addressed with the prior art as noted above and other problems are addressed by applicant's invention as summarized below.